Ballast device having active ballasting circuit and method thereof

ABSTRACT

A ballast device having active ballasting circuit and method thereof, which are used for controlling a HID lamp&#39;s power supply real-timely and steadily, comprising: a power supply unit in said ballast device for generating an outer working voltage, which has a DC-DC transformer to step down the output voltage; a micro control unit, which fetches the parameters of the ballast device other than itself or the HID lamp&#39;s various working status and generates a predefined load current by these parameters; a PWM control unit, which has a PID control module, the PID control module calculates said predefined load current and the HID lamp&#39;s practical load current, and makes said DC-DC transformer change it&#39;s output voltage by the calculate results. The present invention has a simple structure and can change the load current real-timely and steadily.

TECHNICAL FIELD

The present invention relates to a ballast device and a method accordingto said ballast device, especially to a ballast device, which is embedwith a power supply unit, and controls circuit by a micro control unit;and a method according to said ballast device.

DESCRIPTION OF RELATED ARTS

Presently, most of light source for projector is a kind of HID (HighIntensity Discharge). To avoid of damaging caused by an unsteady powersource or an improper manipulation, the projector must have a steadypower control device. The existent power control device 1′ of a HID lampas shown in FIG. 1, comprises a power supply 10′ and a ballast 20′therein. The power supply 10′ and the ballast 20′ are set respectively,especially in the part of assistant power circuit 115′ and 220′.

The operational mode of the existent power control device 1′ of a HIDlamp as shown in FIG. 1: firstly, said power supply 10′ is activated toreceive the input electrical source (AC95V˜230V) 100′. Then an EMI(Electro Magnetic Interference) Filter 105′ in said power supply 10′wipes off EMI. A PFC (Power Factor Correction) 110′ transforms the ACinput electrical source 100′ into DC and divides it into two route, oneof them inputs into the ballast 20′, and be stepped down by the DC-DCtransformer 200′, then be inverted into practical working voltage by theDC-AC transformer 205′ to supply the HID lamp 30′.

But what should be noticed is the ballast mode of said ballast 20′, itis passively detecting the lamp's practical current, then controllingthe current via the transfer function of a PWM (Pulse-Width Modulation)215′. Otherwise, circuit of the present ballast is more complex due toan extra assistant power circuit 220′ is needed for support the workingvoltage to the ballast 20′. Moreover, because the ballast 20‘passivelydetects the lamp’s practical current, it can't steadily control thepower real time

SUMMARY OF THE INVENTION

A main object of the present invention is to provide a ballast devicehaving active ballasting circuit and method thereof, make a power supplyembedded into a ballast, so the ballast's working power can be suppliedby the power supply unit directly, and then incorporate the formerly twopower circuits into one without adding any assistant power circuits likeexisting technology, so it can save cost and predigest the whole ballastsystem.

A subordinate object of the present invention is to provide a ballastdevice having active ballasting circuit and method thereof. It activelydetects and ballasts the lamp's practical current by a MCU (MicroControl Unit) and thereby controls a HID lamp's start-up processsteadily and real-timely.

Another subordinate object of the present invention is to provide aballast device having active ballasting circuit and method thereof. Itdetects the working status of the ballast or the HID lamp via a MCU asits referring outer parameters and real-timely transforms the practicalactive current of the HID lamp.

In accordance with the present invention, said active ballasting device,which is used to steadily control a load module (such as a HID lamp)'scontrol power, comprising: a power supply unit, a micro control unit,some detection modules and a PWM control unit.

The power supply unit is used to receive an electrical source,comprising: an EMI Filter for filtering EMI in the electrical source, aDC-DC transformer for stepping down the voltage that inputted into theDC-DC transformer, a PFC for transiting said filter AC to DC andoutputting to said assistant power circuit and said DC-DC transformerrespectively, and a DC-AC transformer.

Some detection modules are used to detect the working status of theballast (except for the micro control unit) and/or the HID lamp as outerparameters for said MCU's reference. The MCU uses said outer workingvoltage directly, and generates said predefined load current accordingto said outer parameters.

The PWM control unit, which uses a PID control module to calculate saidpredefined load current and the load module's practical load current,and makes said DC-DC transformer change it's output voltage according tothe calculate result, thereby transforms the load module's practicalload current real-timely and steadily.

Besides above, an active ballasting method according to the presentinvention for steadily controlling a ballast device and the practicalload current of the load module such as a HID lamp, comprises:activating power supply unit to receive an electrical source andgenerating outer working voltage by an assistant power circuit; steppingdown the voltage that inputted into a DC-DC transformer by a powersupply unit's DC-DC transformer; detecting the working status of theballast device or the HID lamp as outer parameters for a MCU'sreference; fetching said outer parameters to generate a predefined loadcurrent by the MCU which using said outer working voltage, and furtherjudging whether the outer parameters are in the MCU's predefined rangeto determine to give an information that can be distinguished by user ornot; calculating said predefined load current and said practical loadcurrent by a PID control module; and making said transformer change it'soutput voltage by the result of calculation; and then changing the loadmodule's practical load active current steadily and real-timely.

The present invention has a simple structure, can save cost and simplifythe whole system. The present invention also can change the practicalload current steadily and real-timely.

Other objects, advantages and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sketch map of an existing HID lamp projector's power controldevice.

FIG. 2 is a sketch map of a ballast device according to the presentinvention's preferred embodiment.

FIG. 3 is a working flow chart of a ballast device's MCU according tothe present invention's preferred embodiment.

FIG. 4 is a flow chart of a ballast device steadily controlling a HIDlamp's practical load current according to the present invention'spreferred embodiment.

FIG. 5 is an active characteristic graph of a HID lamp according to thepresent invention's preferred embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 2, a ballast device 1 according to the presentinvention's preferred embodiment for steadily controlling a loadmodule's (e.g. a HID lamp 20) control power, which comprises a powersupply unit 10, a MCU 100, some detection module (not shown) and a PWMcontrol unit.

Said power supply unit 10 receives an electrical source 200 when thepower switch is activated, said power supply unit 10 comprising: an EMIFilter 202 for filtering EMI, an assistant power circuit 235 forgenerating an outer working voltage V_(dd) as the working power of theMCU 100 and for generating an interior working voltage VCC as the powersupply of the rest units, a PFC 204 for transforming the AC power sentby the filter 202 to DC power, dividing it into two routes, andoutputting them into said assistant power circuit 235 and said DC-DCtransformer 208 respectively, a DC-DC transformer for stepping down thevoltage which is inputted the DC-DC transformer and transforming it intothe output voltage V_(o), a DC-AC transformer 210 for electricconnecting with said MCU 100 and inverting DC power to AC power.

Some detection units each comprises some specifically resistant andoperational amplifiers, which is set nearby the PFC 204, the DC-DCtransformer 208 and the HID lamp 20, and electric connects with said MCU100 for detecting working status such as said PFC 204's output voltageV_(s), said DC-DC transformer 208's output voltage V_(o), the HID lamp20's temperature T or the practical load current I_(o) as the outerparameters of said MCU 100.

The MCU 100 directly uses said outer working voltage and generates apredefined load current I_(p) according to outer parameters such as theHID lamp's practical load current I_(o). Moreover, the MCU 100 canfurther judge whether every received or fetched different outerparameters are in the MCU's predefined range to determine whether togenerate information (e.g. alarm information) that can be distinguishedby user or whether start control circuit. Further more, a UI may be seton said ballast device 1 for predefining said outer parameters (e.g. theHID lamp's 20 predefined load current I_(p)) by user or the MCU 100. Ina preferred embodiment of the present invention, the MCU 100 may chooseANALOG's ADUC812.

The PWM 220 has a PID control module 225 which can calculate said loadcurrent I_(p), the HID lamp's 20 practical load current I_(o) and theerror value between above said two currents and can make said DC-DCtransformer 208 properly adjust its output voltage V_(o), then adjustthe HID lamp's practical load current I_(o) steadily and real-timely.

Therefore, an active ballasting device 1 according to the presentinvention embody a power supply 10, which can directly supply theworking power that the ballast device needed, so it can save a workingpower circuit module that the existing technique has. Secondly, theballast device 1 according to the present invention has a MCU 100, so itcan predefine the HID lamp's 20 predefined load start-up current I_(p)by a program, at the same time it can detect the HID lamp's practicalload current, and then the PID control module 225 calculates saidcurrent, so the intent of real-timely and actively controlling the HIDlamp 20's practical load start-up current I_(o) can be achieved.

Referring to FIG. 2, the active ballasting method for steadilycontrolling the control circuit between the control ballast 10 and aload module (e.g. the HID lamp 20) according to the present inventioncomprising as follows step:

Firstly, activating the power switch to make the power supply unit 10receive an electrical source 200, and filtering (comprising bridgerectification) EMI by an EMI filter 202. Secondly, transforming ACvoltage to DC voltage by a PFC and separating into two routes to output,one of them acts as the input voltage of the assistant power circuit235, another is inputted into the DC-DC transformer and be stepped downas the output voltage V_(o). The voltage that is inputted into theassistant power circuit 235 will be ulteriorly separated into two routesto output, they are the assistant power V_(dd) and V_(cc), V_(cc) act asthe assistant power's main output namely power supply, V_(dd) act as theworking power of else chip such as the MCU 10. Otherwise, the DC-ACtransformer 210 invert said output DC voltage V_(o) to AC whichfrequency is 400 Hz acting as the HID 20's practical load voltage.

After the power is activated, the PID control module 225 calculates withthe output predefined load current I_(p) of the MCU 100 and the HID lamp20's practical load current I_(o) that detected by said detectionmodule. The DC-DC transformer 208 properly adjusts the output voltageV_(o) according to the result, thereby adjusts the HID lamp 20'spractical load current I_(o), in accordance with the practical loadcurrent I_(o), the MCU 100 can trace the predefined load current I_(p)real-timely, in this way the intent of limiting the start-up current isachieved.

The detailed working flow about said MCU 100 can further refer to FIG.3, and comprises:

-   -   Process S300 and S302, when the whole system is initializing,        the MCU 100 tests itself;    -   Process S304, judging said test pass or not, if not generating a        flag in a buffer storage and giving a warning message to notice        user;    -   Process S310, activating the PFC 204 to output voltage V_(s);    -   Process S312, judging whether the PFC 204 has output voltage,        that is to say judging whether the PFC 204 is in working order;        if not, the MCU 100 sends an error message and ends the whole        working flow;    -   Process S316, the MCU 100 outputs an inverted waveform to        control the DC-AC transformer 210 to transform Vo into AC        voltage and supply to the HID lamp 20;    -   Process S318, judging whether the HID lamp 20's practical load        current I_(o) has been detected, that is to say judging whether        the HID lamp 20 is in working order, if not, the MCU 100 sends        an error message and ends the whole working flow;    -   Process S322, according to the detected HID lamp 20's practical        load current I_(o), the MCU 100 outputs the predefined load        current I_(p);    -   Process S324, fetching various outer parameters which the        detection module has detected, such as activating the PFC 204        for outputting the voltage Vs, the DC-DC transformer's        outputting voltage V_(o), the HID lamp's temperature T and the        practical load current I_(o); and    -   Process S326, judging whether said outer parameters are in the        predefined range; if not, in process S328, the MCU 100 sends an        error message and ends the whole working flow;

Referring to FIG. 4, it is a flow chart of a ballast device steadilycontrolling a HID lamp's practical load current according to the presentinvention's preferred embodiment, the process comprising:

-   -   Process S400, S402 and S405, using the PID control module to        calculate with said MCU 100's output predefined load current        I_(p) and the HID lamp 20's practical load current I_(o);    -   Process S410, making the DC-DC transformer 208 properly adjust        its output voltage V_(o) according to said calculate result;    -   Process S415, because the adjustment of output voltage V_(o), we        can real-timely adjust the load module's practical load active        current; and    -   Process S415, detecting the practical load current I_(o) of the        HID lamp 20 again, and outputting the predefined load current        I_(p) according to the detected practical load current by the        MCU 100, such in cycles, till achieving the aim of steadily        controlling the active current I_(o). Referring to FIG. 5, FIG.        5 is an active characteristic graph of a HID lamp according to        the present invention's preferred embodiment. It can be found        that: at the beginning of the HID lamp 20's startup, the HID        lamp 20's practical load active current is 150% or so of the        normal current, conversely the voltage and power are only        20%-40% of the normal value. But after the HID lamp 20's current        is steadily controlled, the practical load current will        gradually decline, however the voltage and power will gradually        rise. It needs 1.5 min or so, the voltage and power arrive the        normal value and stop rising. In this way, the present invention        can protect the HID lamp 20 and the circuits in the ballast        device efficiently.

From above it is to be understood, the ballast device according to thepresent invention controls all power circuits with the MCU 100;comprising:

-   -   1. Outputting an invert waveform, namely inverting DC power to        AC power by the DC-AC transformer 210.    -   2. Fetching the HID lamp 20's practical load current Io, the        detection module collects the output current Io's voltage and        inputs it to the MCU 100.    -   3. Fetching the DC-DC transformer 208's output voltage Vo, which        is collected and inputted to the MCU 100 by the detection        module.    -   4. Fetching the PFC 204's output voltage Vs, which is collected        and inputted to the MCU 100 by the detection module.    -   5. Controlling the HID lamp's load startup current steadily.        Because the MCU 100 has a D/A CONV, we can predefine load        startup current and make the practical load current and        predefined load current voltage equal by the PID control        module's character, so we can change output voltage by the DC-DC        transformer 208 to achieve the intent of changing output        current.

Sum up of the above, the ballast device having active ballasting circuitand the method of the present invention have a power supply unitdirectly supplies the working power that the ballast needed, so it cansimplify the whole system and saves cost. Secondly, the presentinvention uses a MCU to fetch various working status as its outerparameters for active ballasting, so it can control a HID lamp start-upprocess steadily and real-timely.

It is to be understood, however, that even though numerouscharacteristics and advantages of the present invention have been setforth in the foregoing description, together with details of thestructure and function of the invention, the disclosure is illustrativeonly, and changes may be made in detail, especially in matters of shape,size, and arrangement of parts within the principles of the invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

1. A ballast device, comprising: a power supply unit for receiving anelectrical source, said power supply unit has an assistant power circuitfor generating outer working voltage, and a transformer for transitingthe voltage that inputted it; a micro control unit, which directly usessaid outer working voltage and generates a predefined load current; anda PWM control unit, which uses a PID control module to calculate saidpredefined load current and the load module's practical load current,and makes said transformer change it's output voltage by the calculateresult.
 2. The ballast device as claimed in claim 1, wherein saidtransformer is a DC-DC transformer, which can step down the voltage thatinputted it.
 3. The ballast device as claimed in claim 1, wherein saidballast has a user interface, by which a user can predefine saidpredefined load current.
 4. The ballast device as claimed in claim 2,wherein said power supply unit further comprises an EMI filter forfiltering EMI in the electrical source; a PFC for transiting the ACtransmitted by said filter to DC, and outputting said DC power to saidassistant power circuit and said DC-DC transformer respectively.
 5. Theballast device as claimed in claim 4, wherein said ballast devicefurther comprises some detection modules for detecting the outerparameters except for said micro control unit's parameters, and offersaid outer parameters to said micro control unit.
 6. The ballast deviceas claimed in claim 5, wherein said micro control unit further refer atleast one outer parameter, said out parameters comprising said loadmodule's practical load current to generate said predefined loadcurrent.
 7. The ballast device as claimed in claim 6, wherein said microcontrol unit further judges whether the outer parameters are in therange of said micro control unit predefined to decide whether togenerate a identifiable message.
 8. The ballast device as claimed inclaim 7, wherein said micro control unit further judges whether theouter parameters are in the range of said micro control unit predefinedto decide whether to control said units except for said micro controlunit.
 9. The ballast device as claimed in claim 8, wherein said outerparameters further comprise said load module temperature, the outputvoltage of said DC-DC voltage transformer or the output voltage of saidPFC.
 10. The ballast device as claimed in claim 9, wherein said ballastdevice further comprises a DC-AC transformer, which connects with saidmicro control unit, wherein said micro control unit's electricconnection can generate an invert wave to control DC-AC transformeraccording to user's demand.
 11. The ballast device as claimed in claim1, wherein said assistant power circuit of said power supply unitfurther generates an interior working voltage to supply said unitsexcept for said micro control unit.
 12. A ballast method, comprisingthereinafter process: activating a power supply unit for receiving anelectrical source, and generating an outer working voltage by anassistant power circuit; transiting the input voltage of a transformerin said power supply unit; generating a predefined load current withsaid outer working voltage by a micro control unit; calculating saidpredefined load current and said practical load current by a PID controlmodule; and making said transformer change it's output voltage by theresult of calculation.
 13. The ballast method as claimed in claim 12,wherein said transformer is a DC-DC transformer, which can step down thevoltage that inputted it.
 14. The ballast method as claimed in claim 12,wherein said power supply unit further comprises an EMI Filter forfiltering EMI in the electrical source; a PFC for transiting the ACtransmitted by said filter to DC, and outputting said DC to the saidassistant power circuit and DC-DC transformer respectively.
 15. Theballast method as claimed in claim 12, wherein said ballast methodfurther comprising: a user can predefine said predefined load current inthe micro control unit by a user Interface.
 16. The ballast method asclaimed in claim 14, wherein said ballast method further comprising:detecting at least one outer parameter except for said micro controlunit's for said micro control unit's reference.
 17. The ballast methodas claimed in claim 16, wherein said ballast method further comprising:said micro control unit generates said load current when the outerparameters that said micro control unit referred comprising said loadmodule's practical load current.
 18. The ballast method as claimed inclaim 16, wherein said ballast method further comprising: furtherjudging whether the outer parameters are in the range of said microcontrol unit predefined to decide whether to generate a identifiablemessage.
 19. The ballast method as claimed in claim 18, wherein saidballast method further comprising: further judging whether said outerparameters are in the range of said micro control unit predefined todecide whether to control the units except for said micro control unit.20. The ballast method as claimed in claim 19, wherein said outerparameter further comprises said load module temperature, the outputvoltage of said DC-DC voltage transformer or the output voltage of saidPFC.
 21. The ballast method as claimed in claim 12, wherein said ballastmethod further comprising: generating an inverter wave by said microcontrol unit to control said DC-AC transformer.
 22. The ballast methodas claimed in claim 12, wherein said ballast method further comprising:generating an interior working voltage to supply said units by anassistant power circuit of said power supply unit.
 23. A ballast method,comprising thereinafter process: receiving an electrical source andgenerating an outer working voltage by a power supply unit in theballast device; detecting the parameters about at least the powersupply's and/or the load module's except for the micro control unit's;receiving said outer working voltage and referring said outer parametersto generate a predefined load current by said micro control unit;calculating said predefined load current and said load module'spractical load current by a PID control module; and changing said loadmodule's practical active current real-timely by the result ofcalculation.
 24. The ballast method as claimed in claim 23, wherein saidballast method further comprising: generating an invert wave by saidmicro control unit to control DC-AC transform.
 25. The ballast method asclaimed in claim 23, wherein said power supply unit further comprising:an EMI Filter for filtering EMI in the electrical source; a PFC fortransforming AC sent by said filter to DC; an assistant power circuitfor generating outer working voltage, and a DC-DC transformer fortransforming the voltage controlled by said PID control module.
 26. Theballast method as claimed in claim 25, wherein said outer parameterfurther comprises said load module's temperature, the output voltage ofsaid DC-DC voltage transformer or the output voltage of said PFC. 27.The ballast method as claimed in claim 26, wherein said ballast methodfurther comprising: said micro control unit generates said load currentwhen the outer parameters that said micro control unit referredcomprising said load module's practical load current.
 28. The ballastmethod as claimed in claim 27, wherein said ballast method furthercomprising: said micro control unit further judges whether the outerparameters are in the range of said micro control unit predefined todecide whether to generate a identifiable message.
 29. The ballastmethod as claimed in claim 28, wherein said ballast method furthercomprising: said micro control unit further judges whether the outerparameters are in the range of said micro control unit predefined todecide whether to control the units except for said micro control unit.